The present invention relates to a drill string component for use at drilling with a liquid driven down-the-hole drilling machine.
In a prior art drill string component of the above mentioned kind, DE-A-30 15 695, the drill string component is provided with coaxial tubes in order to form three coaxial channels for conducting driving liquid to and from the down-the-hole drilling machine and for conducting flushing medium, air or water, to the drill bit for flushing of the drill hole. A drawback with this solution is that the two inner tubes which protrude from the outer tube in order to sealingly cooperate with the corresponding tubes of an adjacent drill string component easily can be damaged when the drill string component is mounted in a drill string or when the drill string component is transported. Furthermore, it is easy to damage the inner tubes when the drill string component is connected to another drill string component, hammer device or rotary device because one must first push the inner tubes into the adjacent component and only then screw the outer tubes together.